Duplicating apparatus



April 28, 1970 w u ET AL 3,508,823

A DUPLIGATING APPARATUS Filed Feb. 5, 1968 2 Sheets-Sheet 1 INVENTORS R0 BERT W. GUNDLACH SEVOLOD S. M H JLQV BY ATTORNEYS Filed Feb. 5, 1968 R. w. GUNDLACH ET AL DUPLICATING APPARATUS 2 Sheets-Sheet z FUSING INVENTO ROBERT W. GUNDLA Y SWSMIH LOVZ United. States Patent Olfice 3,508,823 Patented Apr. 28, 1970 Int. Cl. G03g 15/14 U.S. Cl. 3553 6 Claims ABSTRACT OF THE DISCLOSURE A machine which is capable of making multiple copies of an electrostatic latent image. The electrostatic latent image is developed with a toner composition comprising a vaporizable color producing agent. A specially salt- 'treated copy paper then contacts the developed image, in

the presence of heat, and a reaction between them causes a visible image on the copy paper, and multiple copies may be made.

BACKGROUND OF THE INVENTION 7 This invention relates to a duplicating process and more specifically to an imaging system utilizing vaporizable color producing reagents and is a continuation-in-part of application Ser. No. 276,108, filed Apr. 26, 1963, which in turn is a continuation-in-part of application Ser. No. 185,048, filed Apr. 4, 1962.

Due to the enormous amount of paper work involved in business administration, there has developed a great interest in reducing the time expense generally involved producing multiple copies by the many various methods presently available. For example, it has been a common practice in clerical work to utilize carbon paper in the reproduction of copies of original copy. Aside from the limited number of legible copies that may be produced, this technique is burdened with several inherent deficiencies. For example, the texture of the paper used in making copies must generally be extremely light weight in order to transmit pressure for at least two or three copies. In addition, in the event that more than a couple of copies are desired, it is necessary to exert extremely high pressures on the type character resulting in the embossment of the original. Moreover, the readability of the carbon copies drops off with each additional reproduction.

In order to overcome the many difiiculties inherent in the production of duplicates with carbon paper, a number of duplicating systems utilizing variously formed printing masters have been developed such as spirit duplicating, adherography, and thermography. A spirit duplicating process is a method whereby a master is prepared by typing or writing, resulting in thetransferral of a wax like material to the surface of a master sheet. A duplicating machine moistens the wax like image with a spirit solvent as it presses it against the surface of a copy paper thereby transferring a duplicate of the original image thereto. Adherography is a method of duplicating whereby copy material in theform of an image will selectively absorb infrared radiation. Heat is radiated in the image areas of the original document thereby producing a selective softening of an underlying transfer sheet con: taining a volatile transfer material and permitting transfer of the volatile or otherwise tacky material to a copy sheet in an imagewise configuration. It is then generally necessary to develop the transfer image with adry powder. Thermography is a copying process wherein a special heatasensitive paper is sandwiched in between an original and a copy sheet and exposed to infrared radiation. Selective absorption brings about a reaction between a component in the heat sensitive paper coating and a component in the copy sheet thereby producing a colored image.

While basically these systems have been found useful for duplicating purposes, there are inherent disadvantages to their use. Generally speaking, these techniques are prohibitive in cost if they are used to produce a relatively small number of copies of an original. At the present time, the master copy is usually prepared by typing, printing, writing or drawing the desired material onto a sheet of master paper or by direct contact exposure using special ribbons, carbon papers, inks or other similar imaging sources. These methods of producing the masters are both tedious and time consuming and require highly skilled personnel to produce reliable and valuable reproductions. All these factors substantially increase the cost of the respective duplicating process.

Therefore, it is an object of this invention to provide a duplicating system which will overcome the above noted disadvantages.

It is a further object of this invention to provide a novel duplicating system.

Another object of this invention is to provide a duplicating apparatus using a novel printing master.

Yet, still a further object of this invention is to provide a novel xerographic duplicating apparatus.

SUMMARY OF THE INVENTION The foregoing objects an others are accomplished in accordance with the present invention, generally speaking, by providing a duplicating apparatus provided with a means to form an electrostatic latent image representative of the original image to be reproduced, a means to develop said electrostatic latent image with a toner composition comprising a vaporizable color producing reagent and a means of contacting the resulting developed image with the surface of a specially salt treated copy paper, in the presence of heat, such that a portion of the color producing reagent present vaporizes and reacts with the salt component of said copy paper to produce a visible image. The apparatus of the present invention readily provides multiple copies efliciently and economically without impairing the original to be reproduced.

DETAILED DESCRIPTION AND DESCRIPTION OF DRAWINGS The invention is further illustrated in the following drawing wherein:

FIG. 1 is a diagrammatic view illustrating exposure of a xerographic plate to an original;

FIG. 2 is a diagrammatic view illustrating development of the xerographic plate of FIG. 1 comprising the development of the xerographic plate of FIG. 1 comprising the developer composition of the present invention;

FIG. 3 represents the heat developing step of the present invention;

FIG. 4 is a diagrammatic view of a duplicating apparatus according to the present invention;

FIG. 5 is a diagrammatic view of an alternate embodiment of a duplicating apparatus in accordance with the present invention.

Referring now to FIG. 1 there is seen a xerographic plate generally designated 1 comprising a support substrate 2 and a photoconductive surface layer 3. The xerographic plate 1 is exposed selectively by way of light source 4 and lens mechanism 5 to an original to be reproduced 6. The formation of the electrostatic latent image is accomplished in accordance with the conventional process as disclosed in US. Patent No. 2,297,691.

FIG. 2 illustrates the development phase of the process utilizing the developer composition of the present in-.- vention. Although any suitable developingv means maybe utilized, for purposes of the present illustration a magnetic brush development system is represented. As illustrated, the magnetic brush system 10 comprises a magnetic element 11 enclosed in a non-magnetic envelope 12. Brush like bristles 13 comprising ferromagnetic particles are formed under the influence of the magnet 11. The developer or toner composition of the present invention is mixed with the ferromagnetic particles before the formation of the brush like bristles. The mixture is generally referred to as a toner-carrier developer system in which the relatively large ferromagnetic particles carry the smaller toner particles by virtue of triboelectric attraction.

The developer or toner composition of the present invention generally comprises a thermoplastic material and a color producing reagent although, under certain circumstances, the color producing reagent may serve in both capacities. The color reagent, which is herein defined as chemical A may be one' of a number of chemicals for which a reaction partner exists such that when the two are combined, an intensely colored substance is formed. The reaction partner is herein defined as chemical B. Any suitable material may be utilized in the capacity above described for the purposes of the present invention. Typical reaction partners are as follows:

Diaminophenol Hydrochloride. p-Methylaminophenol Sulfate. Dichlorohydroquinone. Thiourea. Chlorohydroquinone. Bromohydroquinone.

Gallic Acid.

Other organic reducing substances. Ammonia salts.

Ammonium Benzoate. Ammonium Acetate. Ammonium Carbonate.

() (5) Organic diazonium salts and similar.

It has been found that certain of the chemical A constitutes such as rubeanic acid (dithiooxamide) in their common commercial powder forms, are suitable to be used with the conventional magnetic brush carrier particles alone as described in US. Patent 3,015,305. However, conventional resinous materials may be added in such instances to the particular color producing reagent of the developer composition in order to enable fusing of the developer particles in an imagewise configuration. A rubeanic acid developer may also be produced by the same techniques as conventional xerographic toners wherein the colorant reagent is blended with the resinous toner material in place of the generally utilized pigment. Where a good visible xerographic image is desired both conventional pigment and the color producing reagent may be added together. In addition, the resinous material in the toner composition generally helps control the evaporation of the color producing reagent, such as the rubeanic acid, during the duplicating phase of the process thereby permitting greater uniformity over a larger number of copies and reducing ghosting.

As mentioned above, although the illustration represents a magnetic brush development system, other forms of xerographic development may be utilized such as cascade development as described in US. Patents Nos. 2,-

scribed in US. Patent No. 2,221,776 and fur brush development as described in US. Patent No. 2,811,465.

Any suitable resinous material may be used in the developer composition of the present invention such as those disclosed in U.S. Patents Nos. 2,788,288; 3,079,342 and Reissue Patent 25,136. Typical resinous materials are both substituted and unsubstituted styrene polymers such as the Piccolastic resins commercially available from the Pennsylvania Industrial Chemical Corp.; phenol formaldehyde resins and other similar resinous materials.

The developed image on the xerographic plate may then be used in the duplicating process of the present invention by a direct thermographic transfer to a copy sheet pretreated with a reaction partner as set out as chemical B above in a manner illustrated in FIG. 3. A treated copy sheet 15 is placed on top of the xerographic duplicating master 1 and a heated roller 16 is passed over the back of copy sheet 15 so that heat from the roller passes through sheet 15 and causes the color producing reagent present in the developer composition to vaporize, thereby reacting with the salt component contained in the copy paper to produce a visible image. A mirror reverse image would initially be formed on the xerographic plate so that a vapor thermographic transfer directly to a treated copy sheet produces a direct reading image. However, if desired, the image may be formed on a xerographic plate in a direct reading manner and after development the resulting image transferred to the surface of an intermediate substrate utilizing conventional xerographic transfer techniques, such as electrostatically or adhesively upon contact, and the resulting transferred image in turn utilized as the master and the heat treated upon contact with the final copy paper.

FIG. 4 represents a complete system apparatus of the present invention utilizing an intermediate master. A xerographic drum 50 is electrostatically charged by charging device 51, represented herein as a corona discharge device, and exposed to a light pattern of the original 41 by means of light source 42, lens 43, mirror 52, and projection slip 53. The original 41 and drum 50 are moved synchronously in accordance with slip projection techniques by motor 55. After exposure, the electrostatic latent image formed on the surface of the xerographic drum is developed with a developer composition of the present invention as depicted by way of cascade development structure 56. The developed image is transferred to an intermediate drum 57 under the influence of a transfer potential applied to the drum by means of a voltage source 58. Although not necessary for operability of the system, image fusing means 60, depicted as a vapor fusing chamber, can be used for liquifyingand fusing the toner composition. Although any suitable fixing apparatus may be utilized, vapor fusing is preferred in that it does not cause the color producing reagent present in the developer composition to evaporate during the fusing phase of the operation. As set out above, the use of a resinous material in conjunction with the color producing reagent improves the uniformity of reproduced copy. During transfer of the developed image from the xerographic drum 50 to the intermediate master or drum 57, the intermediate master is supported firmly against the xerographic drum by cam 61 positioned as illustrated. After transfer of the image to the intermediate drum 57, cam 61 is rotated to separate the xerographic drum from the intermediate drum. Copy sheets 45 treated with a reaction partner as set out above are then fed by feed mechanism 62 between the intermediate master 57 and a heated roller 63. As a result of the heating process a portion of the color producing reagent present in the toner composition vaporizes and reacts with the salt component of the copy paper to produce a visible image in multiples as desired. With the xerographic drum separated from the intermediate master during duplicating, the final copies can be made at a higher speed independently of speed limitations in the 638,416 and 2,618,551, powder cloud development as deformation and transfer of the xerographically formed and developed image. After the desired number of copies are produced, cleaning web 65 is brought into position against the intermediatemaster by means of a pivot roller 66 in order to clean residual image material from the intermediate master. The cleaning web 65, such as described in US. Patent No. 3,190,198, is operated by a motor 67 and is preferably run in a reverse direction from the rotation of the master for optimum cleaning results. Before reimaging of the xerographic drum, the surface of drum 50 is cleaned by cleaning brush 68.

Any suitable photoconductive material may be used in the xerographic plate of the present invention. Typical inorganic photoconductor materials are sulfur, selenium, zinc sulfide, zinc oxide, zinc cadmium oxide, cadmium sulfoselenide, cadmium selenide, cadmium sulfide, arsenic d-isulfide, arsenic trisulfide, arsenic triselenide, aluminum oxide, lead oxide, molybdenum sulfide, molybdenum selenide, aluminum selenide, aluminum sulfide, aluminum telluride, gallium sulfide, and mixtures thereof. In addi'tion, many suitable organic photoconductor material may be utilized such as doped polyvinyl car-bazole and various phthalocyanine compositions.

When used in conjunction with the apparatus disclosed in FIG. 4, the xerographic plate of the present invention will generally consist of a reusable photoconductive material such as selenium, and doped polyvinyl carbazole. However, in some instances an apparatus may be desired which utilizes the same material for both the xerographic plate and the duplicating master. Thus, the elec- =trostatic latent image will be developed, the resulting toner image fixed thereto, and the subsequent master used to produce the multiple copies. In these instances, it is preferable to use a material which may economically by discarded thereby falling into a category of being non-reusable. For this purpose, a photoconductive or xerographic composition such as zinc oxide in an insulating resinous binder coated on a suitable substrate, such as paper, may be utilized. Other typical photoconductor materials that may be used in a similar system are disclosed in US. Patent No. 3,121,006.

An embodiment of an apparatus suitable for utilization in conjunction with a non-reusable xerographic plate is illustrated in FIG. 5. For purposes of the present illustration the original to be reproduced is depicted as a reel of microfilm 70 from which a light pattern is projected by means of a light source 71, lens mechanism 72 and exposure slit 73. A latent electrostatic image is formed on xerographic web 75 which is, in the present instance, represented as a web of zinc oxide paper. Web 75 is fed from supply reel 76 through charging device 77 represented herein as a corona charging mechanism, past exposure slit 73 to development apparatus 78 herein represented as a magnetic brush system. The magnetic brush development apparatus 78 carrying the developer composition 83 of the present invention is rotated in a direction indicated by the arrow by a motor 80 with the developer particles contacting the imaged web 75 thereby developing the electrostatic latent image, as discussed above. Web 75 supported on rollers 84 is carried after development into a vapor fusing chamber 85 wherein the toner composition of the image is fused to the surface of the web. Web 75 next leaves the fusing station 85 to pass through a selective number of copying stations. Each copying station comprises a feed roll 86 for the metal salt treated copy paper 87 and a heated roller 88 which presses the paper 87 against the web 75 to effeet the vaporization and subsequent color producing reaction and visible image on the copy paper. Backup rollers 90 are provided at each imaging station. Solenoid actuated positioners 91 are connected to each of the heated rollers 88 to enable selectable operation of each of the dupicating stations. For example, if only one copy is desired, then solenoid '91 will be actuated in each duplicating station except one in order to retract the heated rollers thereby preventing imaging. After passing through the duplicating stations, web 75 is wound on takeup reel 92. Movement of web 75 and of the original to be reproduced are operated synchronously by means of motor 93. The web 75, after being wound up on takeup reel 92 can be reused at a later time for running of further copies. For example, a sheet representing a particular page of copy may be cut off the reel of used web and mailed with or without duplicating copies so that further copies may be run off from it at a distant location and at a later time.

Any suitable heating device may be utilized to carry out the present invention such that it is capable of vaporizing the color producing reagent present in the developer composition. Typical heat units are fiash lamps, infrared lamps, sources for supplying intense radiant elimination, sources for supplying hot air by blowers or convection currents, heated rollers or cylinders, and various electrical heating means. Various commercial machines may also be used as the heating component such as thermoprocessing machines commercially available under the trade name Thermofax from Minnesota Mining and Manufacturing Co. and thermoprocessing machines available under the trade name Kalfax, commercially available from the Kalvar Corp. of New Orleans, La.

Although the above discussion in many instances was very specific in terms of conditions and materials used, any of the above listed typical materials may be substituted when suitable in the above systems with similar results. In addition to the means used to practice the process of the present invention, other steps and equivalent modifications may be used, if desirable. For example, heat may be applied to the backside of the photoconductive plate instead of the back of the copy paper in order to obtain results desired. In addition, other materials may be incorporated in the photocollective plate, developer composition or copy paper which will enhance, synergize, or otherwise disirably effect the system of the present invention. For example, the photoconductive plate may contain sensitizers so as to extend the range of the photoconductivity of the plate.

Anyone skilled in the art will have other modifications occur to him based on the teaching of the present invention. These modifications are intended to be encompassed within the scope of this invention.

What i claimed is:

1. A xerographic duplicating apparatus comprising in combination:

(a) means to place an electrostatic charge on the surface of a flexible photoconductive substrate,

(b) exposure means to selectively dissipate said charge to produce an electrostatic charge pattern,

(c) means to develop said electrostatic charge pattern with a toner composition comprising a color producing reagent thereby making visible said electrostatic charge pattern,

(d) means to fix said developed image to the surface of said photoconductive substrate,

(e) a plurality of stations for contacting said image substrate with a plurality of salt treated copy sheets, and,

(f) a plurality of heating elements located at each site of contact made between said photoconductive substrate and said copy sheet.

2. A xerographic duplicating apparatus according to claim 1 wherein said development means comprises a magnetic brush development'system.

3. A xerographic duplicating apparatus comprising in combination:

(a) means to form an electrostatic latent image on the surface of a photoconductive member;

(b) means to develop said latent image with a toner composition comprising a vaporizable color producing reagent;

(c) means to transfer said toner composition in an imagewise configuration to the surface of an image support member;

(d) means to fix said developed image to the surface of said image support member;

(e) a plurality of stations for contacting said image support member with a plurality of salt treated copy sheets; and

(f) a plurality of heating elements generally located at each side of contact made between said image support member and said copy sheet.

4. The apparatus as disclosed in claim 3 further including means to rotate said support member independently of said photoconductive member.

5. A xerographic imaging apparatus comprising in combination:

(a) a rotatably mounted photoconductive member;

(b) means for forming an electrostatic latent image on the surface of said photoconductive member;

v(c) means for developing said electrostatic latent image with a toner composition;

((1) an image support member rotatably mounted in close proximity with said photoconductive member the axis of said support member being parallel to the axis of said photoconductive member;

(h) a plurality of heating elements generally located at each side of contact made between said'image support member and said copy sheet.

6. The apparatus as disclosed in claim 5 wherein said development means comprises a magnetic brush development system.

References Cited UNITED STATES PATENTS 2,874,063 2/1959 Greig 9s 1.7 X 2,990,278 6/1961 Carlson 95-1.7 X 2 3,281,857 10/1966 Kaiser 95-17 X 0 3,318,212 5/1967 Rubin 95-17 JOHN M. HORAN, Primary Examiner 

